In wavelength division multiplexed (WDM) telecommunication networks, optical signals are transported via optical fibers at different wavelengths within a wavelength band. Optical transceivers connected to an optical link, OL, are provided to transmit and receive optical signals. High-speed optical transceivers can use multi-level modulation formats and direct-detection receivers to offer high capacity transmission with low cost, reduced power consumption and low latency of the WDM system. Such transceivers are more vulnerable to chromatic dispersion, CD, related penalties than common receivers using two-level amplitude modulation formats. Examples of such modulation formats being considered for transmission at high data rates are PAM4, DMT and PAM8. These modulation formats require compensation of chromatic dispersion, CD, within tens of ps/nm to minimize any impact of chromatic dispersion, CD. The system's performance can be determined by bit error rate, BER, Q factor, signal to noise ratio, SNR, or other performance metrics. In conventional systems, precise chromatic dispersion estimation and compensation is cumbersome and inefficient for receivers with low chromatic dispersion tolerances. The chromatic dispersion tolerance in the order of no more than ±100 ps/nm chromatic dispersion compensation must be performed very accurately for these systems taking into account even the chromatic dispersion, CD, contributions from optical system components such as arrayed-waveguide gratings (AWG), optical filters, and Er-doped fiber in optical amplifiers.
Accordingly, there is a need to provide method and apparatus for performing automatic compensation of chromatic dispersion very precisely and with minimum cost.